1. Field of the Invention
The invention relates to electrical apparatus and, particularly, to an interlock system for safe operation of microwave ovens.
2. Description of the Prior Art
A source of microwave energy utilized in microwave ovens is the magnetron which is now well known in the art. Such generators provide for radiation of energy within an enclosure to heat any article disposed therein. Radiation of such energy outside of the enclosure in certain instances may constitute harmful exposure and safety standards have been established by regulatory agencies in this area. Magnetron energy generators conventionally operate from regular line sources of low frequency and low voltage which is stepped up to very high DC rectified voltages of approximately 4,000 to 6,000 volts. To provide for safe operation of such apparatus, interlock switches operatively associated with the oven door and/or manual latches have evolved in the prior art to interrupt the line power and, particularly, to interrupt the radiation of energy until the door to the enclosure is closed. Further, such interlock switches prevent serious damage to the expensive equipment and are intended with associated electrical circuitry to substantially reduce any hazards associated with the high voltage supplies.
Other extended periods of time, it has been noted that interlock switches which are continually carrying currents of substantial magnitude fail by welding of the contacts in a closed position to render them completely ineffectual as a safety device. In numerous embodiments of microwave ovens plural interlock switches are employed and in some instances additional ones may be employed. It is possible for more than one of these safety switches to fail which further amplifies the problem of providing for safe operation.
A need arises, therefore, with the increased population of microwave ovens for an interlock system which will immediately disable the circuit upon the failure of any interlock means and signal such failure for repair by authorized personnel before a potentially dangerous condition arises.